Rushing through the heart of South America, the Paraguay River is the largest free flowing tributary of the Rio de la Plata Basin, which is the world’s fifth largest basin and South America’s second largest basin. The free-flowing nature of the Paraguay River underpins the very survival of the millions of people and wildlife who live in the watershed, as well as the seven ecoregions through which this major river passes.
The basin covers more than 1.1 million square kilometers – an area more than twice the size of France - and parts of four countries – Argentina, Bolivia, Brazil, and Paraguay. Originating in the Brazilian state of Mato Grosso, the Paraguay River flows 2,612 km. until it meets the Paraná River. The basin spans a range of altitudes with the highest point of 4,500 meters above sea level in the Andes and the lowest point of 50 meters at the confluence with the Paraná.
More than 8 million people and thousands of species call the Paraguay River Basin home, including numerous indigenous and rural communities. There are approximately four times as many cattle as there are people in the Pantanal, making cattle ranching the most important economic activity in the basin, along with agricultural production. Cropland covers nearly 7 million hectares of the basin and include soybean, corn, cotton, rice, and sorghum. The Paraguay River, as the most navigable river in South America after the Amazon in terms of navigable length, serves as a critical link to the Atlantic Ocean and global markets for the land-locked countries and states along the river.
Sprawling over seven ecoregions, the basin encompasses some of the most biodiverse and pristine ecosystems in the world. For instance, the Cerrado, which covers 18% of the basin, is the world’s most biologically rich savanna and harbors 5% of the planet's plants and animals. The other ecoregions include the Andean ecosystem, Andean Yungas, Atlantic Forest, Chaco, Chiquitano Forest, and the Pantanal.
Dozens of tributaries rush down the eastern Andes and the Plateau of the upper basin into the Paraguay River. The main tributaries on the left bank of the Paraguay are Cuiabá, São Lourenço, Taquari, and Miranda, all of which drain into the Pantanal. The main tributaries on the right bank of the Paraguay River are the Pilcomayo and Bermejo.
These rivers are critical for maintaining the Paraguay River’s flow, which sustains the functioning of the Pantanal. A key part of the Paraguay Basin’s hydrology, the Pantanal acts as a “sponge” that retains water draining the upper part of the basin for six months, providing natural flood protection for the millions of people who live downstream in Paraguay, Uruguay, and Argentina. The seasonal rise and fall of the river levels create a wide breadth of habitat diversity, from forests to savanna grasslands to wetlands. The Paraguay River’s flood pulses are widely recognized as the single most important factor underpinning the basin’s environmental heterogeneity and associated biodiversity and ecosystem services. All of this is made possible by the free-flowing nature of the Paraguay River.
The Paraguay River originates in the Upper Paraguay River Basin, an area of approximately 600,000 square kilometers that is critical to the management of water resources for the countries that share its waters (Bolivia, Brazil, and Paraguay). The Plateau (Planalto) encompasses 59% of the upper basin while the Floodplain (Pantanal) comprises the other 41 percent. The highlands of the plateau lie mostly in the Brazilian states of Mato Grosso and Mato Grosso do Sul, with dozens of rivers flowing from the highlands into the Pantanal to form a natural, inland reservoir.
About 2.8 million people live in the Upper Paraguay River Basin, working across an array of sectors from mining to tourism to fishing. The most important economic activity in the Basin is cattle ranching at more than 20 million head. Cattle ranching and agricultural production have driven the mass clearing of native vegetation, with 65% of the Plateau and more than 12% of the Pantanal already deforested. Around 100 hydroelectric dams are also proposed for the Upper Paraguay River Basin, in addition to the 38 that already exist, which may cumulatively impair the basin’s natural hydrology.
Effective land use planning and improved enforcement, as well as trinational integrated water management, have been identified as necessary actions to protect the viability of the Upper Paraguay River Basin.
Recent, unsustainable land use changes and a series of infrastructure projects threaten the vitality of the Paraguay River. The extensive expansion of agriculture, especially soy, and cattle ranching have contributed to the loss of roughly a quarter of the basin’s native vegetation.
While the ecological changes are cause for alarm, the basin remains one of the last wild places on the planet. The most pressing challenges are on paper right now in the form of major infrastructure projects. The 3,440-kilometer HidrovÍa Paraguay-Paraná (waterway) has raised the most concern. Proposed to run between Cáceres, Mato Grosso, Brazil to Nueva Palmira, Uruguay, this long waterway would improve river navigation and expand trade for South America’s landlocked but highly productive countries and states. To develop such a navigation system, the Paraguay River Basin would have to undergo extensive dredging, the establishment of canals, excavation of rocky beds, realignment of channels, and the improvement of ports and roads. Despite the economic potential of this project, the consequences are severe: the Pantanal could significantly shrink in size, reducing the wetland’s floodwater retention capacity, while the multiple developments would alter the river’s flood pulse as well as severely disrupt the regional tourism industry and fishermen’s livelihoods. Additionally, the some 100 dams proposed for the Upper Paraguay River Basin cumulatively have the capacity to alter the river’s natural hydrology, which sustains the economies of four countries, the livelihoods of millions of people, and the survival of thousands of species.
All the ecosystems that composes the Paraguay River Basin are interconnected. A modification to any ecosystem affects the entire system. For that reason, WWF is working with partners in Bolivia, Brazil, and Paraguay to guarantee a prosperous future for the Paraguay River Basin through watershed scale restoration projects, studies evaluating the health of the Basin’s environment to inform better decision making, and stakeholder partnerships that emphasize capacity building and certification for best practices around organic cattle ranching and sustainable land use.
In March 2018 at the 8th World Water Forum in Brazil, ministers from Bolivia, Brazil, and Paraguay signed a sustainable development and conservation declaration for the Pantanal, ensuring that a linchpin of the Paraguay River Basin is protected into the future.